There are two very different running techniques: running tall versus running with a slight forward lean. Which is right?
Each person’s running technique needs to be assessed on an individual basis. The debate about leaning slightly forwards aims to encourage athletes to land on their forefoot, creating a falling-forward style, which helps reduce braking forces and speeds you up.
By contrast, landing on your heels (how most people run) encourages a leaning-back and over-striding style. This acts as a braking action – as your upper body mass is behind your heels when the foot hits the ground – which transmits impact through your skeleton, leading to an increase in injuries and slowing you down.
But if you lean too far forward, there is often too much push-off from the toes, creating friction and overuse of the propulsive muscles and connective tissue. This means the body takes time to get centred over the landing foot and has to apply a large propulsive force to take off again, resulting in a braking effect.
What you should do is land lightly under your centre of gravity. Land directly under your body mass to reduce the impact on your skeleton. Your legs should act like springs, as you lift your feet off the ground using your hip flexors. If you lean forward slightly, your body will also move up and down less, leading to quicker recovery, greater efficiency and less impact-related injuries.
Running tall should mean your torso is straight and not crumpling forwards around the shoulders, which often happens due to fatigue. Look forwards and relax the shoulders; if you feel yourself starting to crumple, do some arm circles to stretch out the shoulder girdle.
More abdominal work and improvements in running technique should help resolve the problem.